A core memory fragment can be found inside the Hall of Memories. It will spawn randomly, and the The Archivist will call it on the chatbox, much like a chronicle fragment, it will be immediately visible to all players. It will give the player a core memory fragment which can be put on a plinth in the north-east and north-west corners of the hall. They last around 30 seconds before vanishing.
The update history project is a work-in-progress – not all updates to this topic may be covered below. See here for how to help out!